CVE-2026-2748
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedSEPPmail Secure Email Gateway before version 15.0.1 improperly validates S/MIME certificates issued for email addresses containing whitespaces, allowing signature spoofing.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceSEPPmail Secure Email Gateway versions prior to 15.0.1 contain a validation flaw in S/MIME certificate processing. The gateway fails to properly validate certificates issued for email addresses containing whitespace characters, enabling an attacker to craft malicious certificates that bypass signature verification and facilitate signature spoofing attacks.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data< 15.0.1CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
-
Identify installed SEPPmail Gateway versionAccess the administration interface or check system information to retrieve the current SEPPmail Secure Email Gateway version numberAffected if The installed version is lower than 15.0.1 (for example, 14.x.x or earlier)
-
Verify S/MIME processing is enabledCheck the SEPPmail Gateway configuration for S/MIME certificate handling settings. This may be found in the email security or encryption settings panelAffected if S/MIME processing is actively enabled and configured for inbound or outbound email handling
-
Review S/MIME certificate validation logsExamine the gateway logs for S/MIME signature verification events, focusing on certificate chain validation and email address matching operationsAffected if The system processes S/MIME certificates without rejecting addresses containing whitespace characters
-
Inspect S/MIME certificate configurationAccess the S/MIME settings in the administration console and review the certificate validation rules configurationAffected if Certificate validation is set to process all S/MIME certificates without explicit whitespace filtering in the email address field
You are affected if your SEPPmail Secure Email Gateway version is below 15.0.1 and S/MIME certificate processing is enabled, particularly if certificates with whitespace in email addresses can bypass validation.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped15.0.1
Upgrade SEPPmail Secure Email Gateway to version 15.0.1 or later to remediate the improper S/MIME certificate validation. Review existing S/MIME implementations and consider implementing additional validation checks for certificate email addresses.
15.0.1
- Obtain SEPPmail Secure Email Gateway version 15.0.1 from the official Seppmail download source (downloads.seppmail.com or vendor support portal)
- Follow Seppmail's standard upgrade procedure for Secure Email Gateway products
- Verify the upgrade was successful and the version is 15.0.1
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation3.0 h
- Implementation6.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,224.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-2748 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-2748 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data